Nemesis is the primary antagonist of the anime Saber Rider and the Star Sheriffs, serving as the leader of the Outriders and the mastermind behind their incursions into the human dimension. In terms of background, Nemesis was originally an Outrider but lost his physical body in a past battle against humanity. His brain was subsequently integrated into the Triton Matter, a mysterious tower on the Outrider home planet that serves as an immense energy source. This transformation allowed him to adopt a synthetic cyborg form, and he created the Vapor Trail, a dimensional pathway that enables the Outriders to cross into human space.

Personality wise, Nemesis is depicted as a cynical, witty, and often impatient figure. He displays boredom with his subordinates, whom he considers incompetent, and prefers to command from his throne rather than engage directly in battles. His motivations are rooted in a desire for conquest and control over the human dimension, which he views as resource-rich compared to the barren Outrider dimension. He is strategic and logical, valuing intelligence and efficiency over raw force, and shows no hesitation in sacrificing his own troops to achieve his goals.

In the story, Nemesis functions as the overarching antagonist. He rarely appears in person, typically delegating operations to his lieutenants such as Gattler and Vanquoo. His role intensifies as the series progresses, culminating in the final episodes where his true nature is revealed. Key relationships include his alliance with Jesse Blue, a former Cavalry Command cadet turned traitor, and his direct conflict with Saber Rider, the leader of the Star Sheriffs. Saber Rider is the only member of the team to face Nemesis one-on-one, engaging him in a laser sword duel in the Vapor Zone.

The character undergoes significant development over the course of the series. Early appearances present him as a mysterious, cloaked figure with a robotic skull-like face, often shown seated on his throne. As the Star Sheriffs close in on his stronghold, he eventually discloses that his physical body is merely a remote-controlled cyborg shell; his consciousness and true essence are housed within the Triton Matter. This revelation means that destroying his outward form does not kill him, and he can potentially deploy an unlimited number of identical avatars. His ultimate defeat comes only when the Outrider planet itself is destroyed, causing the Triton Matter to explode.

Notable abilities include direct control over the Nth degree, a source of enormous energy, as well as the capacity to operate multiple cyborg bodies simultaneously. He also possesses the strategic knowledge to create and maintain the Vapor Trail, which is essential for the Outriders’ dimensional travel. While not a frontline combatant, his technological superiority and vast resources make him an extremely formidable and elusive adversary.